Flat detectors are operated at different amplification levels, in order to be able to cover a dose range which is as large as possible. In fluoroscopy applications, for example, the largest analog gain in the detector electronics is selected in order to achieve a desired signal threshold. For recording operation in which high doses are employed, a lower amplification is then used.
Changing the amplifier levels in the detector—7 gain levels are usual in modern equipment—entails switching artifacts which lead to degradations in the image quality and are directly visible after switching as so-called overshoot processes with reduced image quality. Because of the nonlinearity of the detector within a detector mode, it is not possible to achieve integral linearity over the entire dose range to be covered so that, in the previously available measuring methods, it has also not been possible to reduce the number of amplifier levels and cover a maximally large dose range with one detector mode.